Network protocol


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Network protocol

  1. 1. Network Protocols
  2. 2. Introducing Protocols• Set of predefined rules used by devices in network for data transfer• Network Protocols: – NetBIOS/NetBEUI – TCP/IP – ARP/RARP – ICMP/IGMP – UDP – IPX/SPX – HDLC/SDLC
  3. 3. NetBIOS/NetBEUI• Developed by IBM and later adopted by Microsoft• Network Basic Input/Output System (NetBIOS) used for communication within LAN• Operates at Transport and Session layers of OSI model• NetBIOS Extended User Interface (NetBEUI) adds capabilities to NetBIOS and an advanced version of NetBIOS used in MS Windows OS• Widely used in Ethernet, Token Ring and Windows NT networks
  4. 4. NetBIOS Services• Supports three distinct services: Name service for name registration and resolution, Session service for connection oriented communication and datagram service for connectionless communication NetBIOS Services Session Datagram Name Service Service Service
  5. 5. Name Service• Implemented in Microsoft Windows as Windows Internet Name Service (WINS).• Provides means to application to register its NetBIOS name• NetBIOS names are 16 bytes length• Service uses UDP port 137• Name Service functions include – Add Name – Add Group Name – Delete Name – Find Name
  6. 6. Session ServiceEstablishes session for data exchange between computers using TCP port 139 Session Establishment Process Session Termination Process
  7. 7. Datagram Service• Uses the UDP port 138 and provides a connectionless and broadcast-oriented data communication between two devices.• Divides data in datagrams before sending• Datagram service functions include: – Send Datagram – Send Broadcast Datagram – Receive Datagram – Receive Broadcast Datagram
  8. 8. NetBIOS Name Resolution• Used to map NetBIOS names to IP addresses• Methods used to resolve names: – NetBIOS Name Cache – NetBIOS Name Server (NBNS) – Local Broadcast
  9. 9. NetBEUI• Enhanced version of NetBIOS• Used by LAN manager, LAN server, Windows for workgroups, Windows 95 and Windows NT• Adapted to other protocols such as IPX or TCP/IP as it does not support routing of messages to other networks
  10. 10. TCP/IP• Two layer communication protocol used by Internet• TCP provides connection-oriented reliable transport service• Divides the message into smaller packets called segments• IP is a connectionless and unreliable datagram protocol and provides no error checking• IP transfers data in the form of packets called datagrams
  11. 11. TCP/IP Protocol Suite • Designed before OSI model • Consists of five layers • Provides independent protocols at each layer
  12. 12. Description of each layer - I• Physical and Data link layer – standard and proprietary protocols are supported by these layers.• Network layer – 1. IP – – 2. ARP – – 3. RARP – – 4. ICMP – used to send query and error reporting messages to the sender and not to correct them – 5. IGMP – Uses class D IP address
  13. 13. Description of each layer - II• Transport layer – 1. UDP – – 2. TCP – divides data into segments each having a sequence number – 3. Stream Control Transmission Protocol (SCTP) – multiple streams of data can be transmitted simultaneously. Used over wireless network and transmission of multimedia data. Supports voice over IP and combines the best features of TCP and UDP
  14. 14. Description of each layer - III• Application layer – 1. SMTP – – 2. FTP – – 3. DNS – – 4. SNMP – Based on client-server model – NFS – Allows different Operating systems to share files and disk storage – TFTP – Uses UDP to upload or download files and does not provide security features
  15. 15. TCP Segment Format.
  16. 16. IPv4 Datagram Format
  17. 17. IP Datagram Fragmentation• Fragmentation refers to breaking datagrams into pieces• Maximum Transfer Unit (MTU) is maximum amount of data that frame can carry• Datagram is fragmented when its size exceeds MTU of the network• Fragments follow different paths to reach destination
  18. 18. ARP/RARP• To deliver packet both physical and logical addresses are necessary• Address Resolution Protocol (ARP) provides physical address when logical address is known• Reverse Address Resolution Protocol (RARP) maps logical address to physical address• RARP is useful when device is booted for first time
  19. 19. ICMP/IGMP• Internet Control Message Protocol (ICMP) provides error reporting and query management mechanism• ICMP handles problems occurring while packet transmission• Internet Group Message Protocol (IGMP) manages multicasting and group membership of devices
  20. 20. ICMP Message Types ICMP Messages Error Reporting Query Destination Echo request Unreachable and reply Source Quench Timestamp request and reply Time Exceeded Address Mask Request and replyParameter Problem Router Solicitation and Advertisement Redirection
  21. 21. Error Reporting Messages• ICMP is used for error reporting not for error correcting 1. Destination Unreachable – 2. Source Quench – used for flow control at network layer 3. Time Exceeded - 4. Parameter Problem – if there is an ambiguity in the header part 5. Redirection – if the host forwards datagram destined for some other network to wrong router
  22. 22. Query Messages• Echo Request and Reply – Ping command• Timestamp request and reply –• Address Mask request and reply – If a host knows the IP address but does not know the corresponding mask• Router Solicitation and Advertisement – Used to determine whether the routers in the network are working properly
  23. 23. IGMP Message Types IGMP Messages Membership Query Leave Report ReportGeneral Query Special Query
  24. 24. UDP• User Datagram Protocol (UDP) provides connectionless process-to-process communication• UDP packets are called user datagrams.• User Datagram Format:
  25. 25. UDP Operation - IEncapsulation Decapsulation
  26. 26. UDP Operation - IIClient Queue Server Queue
  27. 27. IPX/SPX• Novell NetWare system uses IPX/SPX as communication protocol within networks• IPX operates at Network layer for connectionless communication• SPX operates at Transport layer for connection-oriented communication• Together, IPX/SPX provides same services as TCP/IP
  28. 28. IPX/SPX Protocol Suite
  29. 29. IPX/SPX Naming Conventions• IPX/SPX/NetBIOS Compatible Transport Protocol (NWLink) uses two types of IPX network numbers for routing purposes: – Internal network number – Mentioned as Internal network number in NWLink IPX/SPX/NetBIOS Compatible Transport Protocol Properties dialog box It’s a hexadecimal number with 1 to 8 digits (1 to FFFFFFFE) – External network number – Mentioned as Network number in Manual Frame Detection dialog box
  30. 30. HDLC/SDLC• DLC protocols are two types: asynchronous and synchronous• High Level Data Link Control (HDLC) and Synchronous Data Link Control (SDLC) are bit-oriented synchronous protocols in which data frames are interpreted as series of bits• Both are useful for half-duplex and full-duplex communication• HP adopted DLC protocol for use by network printers• Windows XP still support DLC
  31. 31. HDLC Nodes and Link Configurations• Types of HDLC nodes are: – Primary Station – transmits frames called commands to secondary stations – Secondary Station – send response frames to primary station – Combined Station• Supported link configurations: – Unbalanced – Balanced
  32. 32. HDLC Data Transfer Modes• Normal Response Mode (NRM) – Secondary station requires permission from primary station before sending data• Asynchronous Response Mode (ARM) – Secondary station can transfer without permission from primary station• Asynchronous Balanced Mode (ABM) – Either of the combined station can initiate the transmission
  33. 33. SDLC• Bit-oriented protocol invented by IBM and similar to HDLC• Only primary and secondary stations are used Configurations Point-to-Point Multipoint Loop Hub go-ahead
  34. 34. Protocols at Different Layers OSI Layers ProtocolsPhysical Layer No protocols definedData Link Layer HDLC, SDLCNetwork Layer IP, ICMP, IGMP, ARP, RARP, IPXTransport Layer NetBEUI, TCP, UDP, SPXSession Layer NetBIOS, SAP, SMTP, FTP, DNS, SNMP,Presentation Layer NCP, RIP, NLSP, SMTP, FTP, DNS, SNMP, NFSApplication Layer SMTP, DNS, SNMP, NFS, TFTP